As is well known in the art of brush seals, the seals have been particularly adapted for use in rotating machinery and are constructed with a bundle of fibers that are oriented radially relative to the rotating or stationary part so that the ends cooperate to seal one area of a rotating machine from another. Typically, the brush seal is comprised of a package consisting of a backing plate, bristles, and a side plate. These three components are welded together to form the package. More often than not the bristles are mounted radially and the seal conventionally requires the use of retaining means such as a retaining plate or snap ring to secure the bristle pack to the carrier.
An exemplary brush seal is disclosed in U.S. Pat. No. 5,090,710 granted to R. F. J. Flower on Feb. 25, 1992 entitled "Brush Seal". As noted therein, the brush seal comprises a seal assemble with a plurality of brush seal elements each of which include a generally arcuate carrier and a plurality of bristles projecting therefrom. The brush seal elements are supported end-to-end to form a continuous wiping surface. The patents disclose seven different examples of designs for supporting the brush seal elements.
U.S. Pat. No. 5,074,748 granted to M. P. Hagle on Dec. 4, 1991 entitle "Seal Assembly for Segmented Turbine Engine Structures" discloses a brush seal utilized to seal the cooling passage from the engine's gas path. This disclosure shows a combination of a radial brush seal and spline seal that serves to seal the segmented components of a segmented shroud and segmented turbine rotor assembly where the brush seal provides continuous cicumferential sealing around the segments and spline seals.
The heretofore known brush seals are typically constructed, as is apparent from the prior art, to include means for securing the brush seal to be concentric with the component being sealed by the bristles. Obviously, when the bristles are mounted in the radial direction the axial loadings have virtually no affect on the bristles. However when the bristles are mounted in the axial direction the axial loads are of paramount consideration. In static structures, as for example, in the interface between the combustor and the first stator of the gas turbine engine, which is a hostile environment, the axial loads are extremely high as a result of large component displacements.
Obviously, in this environment where it is necessary to separate the cool air stream from the gas path so that neither leaks into the other, the engine designer is confronted with a complex problem. The consequence of any leakage at this juncture point particularly after considerable work has been expended on the fluid working medium is a substantial penalty which ultimately affects engine performance.
I have found that I can provide a satisfactory seal at this interface by utilizing an axial load carrying brush seal that eliminates the need for a retaining plate or snap ring as is required in heretofore known designs. The use of a diametral tight fit between the side plate and carrier holds the brush seal package in place without requiring the retaining or snap ring. The brush seal package backing plate serves a dual function of supporting the bristle pack and transmitting the axial loads between components.